非开挖水平定向钻机钻头的类型及适应性分析     

李恒 《岩土钻凿工程》2008,(1):59-62

非开挖水平钻机是非开挖铺管技术的核心机械,直接关系到铺设工程的成败;钻头作为钻机的一个部件,主要起到导向成孔、扩孔和清孔的作用。钻头的选择直接关系到后续拖管的难易程度,因此,根据不同的地质和施工要求应选择相应的钻头。本文就非开挖钻机扩孔钻头的类型及适应性作了详细地分析。  相似文献   

Understanding the latest progress in mitigating climate change and facilitating carbon neutrality北大核心CSCD     

袁佳双  张永香  陈迎  于金媛  王红丽 《气候变化研究进展》2022,18(5):523-530

The Intergovernmental Panel on Climate Change (IPCC) released the report of Working Group III of the Sixth Assessment Report "climate change 2022: mitigating climate change". The report accessed and summarized the latest research progress on climate change mitigation since the release of the Fifth Assessment Report, which will provide an important reference for the international community to further understand climate change mitigation actions, system transformation, and the pursuit of sustainable development. The report pointed out that human activities had cumulatively emitted about 2.4 trillion tons of CO2 from 1850 to 2019, of which 58% was emitted before 1990. In order to control the level of global temperature rise in the future, deep and immediate mitigation actions are required. In both low and minimum emission scenarios, fossil energy needs to be greatly reduced; renewable energy will be the mainstay of future energy supply; achieving carbon neutrality requires relying on negative emission technologies and increasing carbon sinks. Technological progress is one of the key conditions for helping the world combat climate change. Accelerated and equitable climate action is critical to sustainable development. The report's conclusions once again show that China's carbon neutrality target is in line with the mitigation path of the Paris Agreement's temperature rise target of less than 2 °C and striving to achieve 1.5°C. In the future, China should strengthen special research programs on the national concerns and key contents covered in the report. While strengthening scientific interpretation and effective use of the report's conclusions, it is also necessary to actively participate in the IPCC scientific assessment process, actively contribute Chinese wisdom, and contribute to the international dissemination of Chinese climate governance concepts. © 2022 Chinese Journal of Digestive Endoscopy All rights reserved.  相似文献   

气象万千探本索源——南京信息工程大学“大气探测学科”发展历程回顾与展望          下载免费PDF全文

张培昌  顾松山  王振会  魏鸣  官莉  郜海阳  寇蕾蕾 《大气科学学报》2021,44(2):165-177

大气探测学科是大气科学学科重要的核心学科分支之一。我校大气探测学科从1973年创建至今,经47年的风雨征程,几代人的努力与执着,历经重组和调整,始终围绕学校发展目标,将专业建设与国家需求紧密接合,不断探索和加强人才培养、师资建设和提升科研水平,建立了特色鲜明的学科体系,为学校和中国气象事业的发展做出了重要贡献。本文概略介绍了大气探测学科内涵和我校大气探测学科概况,从初始建立、改革发展、发展提升等三个阶段描述学科沿革拓展、师资队伍壮大、实习实验设备、课程教材建设、基础理论技术研究、气象系统开发、学科建设成果及未来发展规划等。  相似文献   

China’s pathway to carbon neutrality for the iron and steel industry     

《Global Environmental Change》2022

As a hard-to-abate sector, the iron and steel industry is responsible for 22% of China’s total carbon emissions and therefore plays a crucial role in achieving China’s carbon peaking and neutrality target. Nearly 90% of China’s iron and steel output is produced with coal-based blast furnaces, which results in high carbon emission intensity. To peak China’s carbon emissions and achieve the carbon neutrality target, it is essential to accelerate the application of breakthrough technologies such as carbon capture and storage (CCS) and hydrogen-based steel-making. This paper estimates the future CO₂ emissions from China’s iron and steel industry in pathways that consider the influence of different technology portfolios, technology maturity, decarbonization of power systems, and future steel production output. The results show that using currently available technology, China’s iron and steel industry can reduce CO₂ emissions by more than 50%. However, it cannot achieve the neutrality target without using innovative technologies. By combining conventional strategies with net-zero emission technologies such as CCS and hydrogen metallurgy, approximately 80–90% emission reduction can be achieved, thus leading to a carbon neutrality pathway, which can meet the 1.5°C targets of the carbon budget limit either. In the future, carbon emissions' reduction potential will be influenced by the decarbonization of power systems and the diffusion rate of innovative technologies. To achieve carbon neutrality, it is essential to act sooner and faster.  相似文献   

Mapping public appraisals of carbon dioxide removal     

《Global Environmental Change》2022

Efforts to deliver on net zero emissions targets are set to rely on carbon dioxide removal (CDR) methods. Democratic, trustworthy and socially intelligent research, development, demonstration and deployment of CDR methods in aid of net zero will be highly dependent on how different publics evaluate them, and ultimately which groups support or oppose them. This paper develops a novel, nationally representative method for the multi-criteria appraisal of five policy relevant CDR methods – plus an option not to pursue CDR at all – by members of the British public (n = 2,111). The results show that the public supports the inclusion of CDR in UK climate policy. CDR methods often characterised as ‘natural’ or ‘nature-based’ are appraised more highly than ‘technological’ ones, in the descending order: habitat restoration, afforestation, wood in construction, bioenergy with carbon capture and storage, and direct air carbon capture and storage. Yet, there is no significant disagreement in the appraisal of technological methods and they therefore may be less polarizing, suggesting that popular preconceptions of what is natural – and therefore more attractive – may be holding them back. CDR methods being mainly developed by public sector and non-governmental organisations are also appraised more highly than those being developed by private interests. Regional differences in option appraisal reveal where particular CDR methods are more or less likely to be supported or opposed; stressing the importance of matching physical requirements for CDR with appropriate social contexts. Demographic and socio-economic analyses show that people who appraise CDR methods most highly tend to be older respondents, male, or of a higher social grade. Finally, those with hierarchical worldviews and who voted ‘leave’ in the UK’s referendum on EU membership are less supportive of CDR than those with egalitarian worldviews and who voted ‘remain’.  相似文献   

Forty‐Nine Major and Trace Element Concentrations Measured in Soil Reference Materials NIST SRM 2586, 2587, 2709a, 2710a and 2711a Using ICP‐MS and Wavelength Dispersive‐XRF          下载免费PDF全文

Harris L. Byers  Lindsay J. McHenry  Timothy J. Grundl 《Geostandards and Geoanalytical Research》2016,40(3):433-445

Excellent agreement was noted in the concentration of major and trace elements in five NIST (National Institute for Science and Technology) soil reference materials (NIST SRM 2586, 2587, 2709a, 2710a and 2711a) between measurement results from wavelength dispersive‐XRF and ICP‐MS from two independent laboratories, and NIST certificate of analysis and literature data. We describe the variability in concentrations of up to forty‐nine elements (plus loss on ignition) and provide values for up to twenty‐one elements previously uncharacterised by NIST in these soil RMs. The additional characterisation provided in this investigation can be utilised to reduce the measurement bias of custom calibration routines and improve the quality of control checks developed using these NIST RMs.  相似文献   

基于GNSS浮标的海岛礁稀少控制DOM生产技术     

买小争  叶冬梅 《测绘科学》2016,41(7):82-87,214

针对远海岛礁多为不可登岛,开展远海岛礁大比例尺测图难度大的问题,该文提出了利用GNSS浮标作为海上控制点,探讨GNSS浮标在海岛礁1∶2 000DOM生产中发挥的作用。采用长航时无人机获取试验岛礁高分辨率影像,在无人机常规航线并加摄构架航线的前提下,结合PPP技术,在海岛四周布设GNSS浮标的控制组合方式进行区域网平差和影像生产。试验结果表明,利用此种方法进行远海岛礁大比例尺DOM生产是切实可行的,精度基本满足海岛1∶2 000DOM生产精度要求,研究成果为远海岛礁1∶2 000DOM生产提供了一套合理的解决方案,为远海岛礁大比例尺测图提供参考。  相似文献   

Hype among low-carbon technologies: Carbon capture and storage in comparison     

《Global Environmental Change》2016

Carbon dioxide capture and storage (CCS) technology has become a crucial part of climate change mitigation strategies around the world; yet its progress has been slow. Some have criticised CCS as a distracting hype, even as mainstream support continues. This article adapts the literature on technological hypes to develop a framework suitable for technologies with limited media/public exposure, such as CCS. It provides a qualitative context and analyses seven quantitative indicators of hype that are largely internal to the CCS technology regime. Throughout, the article contrasts results for CCS with those of comparable technologies. The main findings, which support the view that CCS has been hyped, are as follows. “Expectations” mounted rapidly in the form of project announcements for electricity applications of CCS and deployment forecasts in influential reports. However, announcements soon plummeted. “Commitments” remained high, nonetheless, judging by allocations in public budgets and number of peer-reviewed publications. Meanwhile, “outcomes”—in terms of patents, prototypes and estimated costs—reveal few if any improvements for CCS. Considering these findings and the characteristics of CCS, its development is likely to be more difficult than initially expected. Accordingly, this article calls for decisively prioritising CCS for industrial and, potentially, bioenergy uses. Coal- and gas-fired power plants may be replaced by non-CCS technologies, so power CCS development is far less pressing.  相似文献   

高密度聚乙烯挤出抽丝技术分析     

刘劲科 《广东海洋大学学报》1998,(1)

对在高密度聚乙烯抽丝过程中温度、牵伸比对抽丝质量的影响进行了测试分析。结果表明,机头温度对丝的光泽和柔软性有显著影响,单丝的断裂强度随牵伸比的增大而增大,断裂伸长率随牵伸比的增大而减少。并对抽丝过程的断丝原因进行了分析。  相似文献   

安徽省级资源环境空间信息服务系统研究与开发   总被引：2，自引：0，他引：2  

马众模  陈政  徐振宇  周燕林 《地理科学》2003,23(3):342-347

研究建立一个结构规范、服务便捷的省级资源环境空间信息网，实现资源环境空间信息的网络共享和服务已经是迫在眉睫。安徽省资源环境空间信息网首次在省政府网络上实现了资源环境空间信息的快速访问，具有数据最大、覆盖面全、类型多样的特点，并且采用SuperMap国产GIS软件进行开发，运行稳定、安全可靠，具有很好的可扩展性。系统地介绍了安徽省资源环境空间信息网的系统结构、数据库建设、数据更新和系统的主要功能。  相似文献